From Peace Corps Wiki
Engineering & Architecture Projects
Engineers Without Borders - USA - Open Projects
"EWB-USA is committed to designing and implementing engineering projects in developing communities around the world. There is great need in areas ranging from renewable energy to clean water to sustainable enterprise development."
Open Architecture Network - The Open Architecture Network is an online, open source community dedicated to improving living conditions through innovative and sustainable design.
Small Business Projects
Kiva - Kiva lets you connect with and loan money to unique small businesses in the developing world. By choosing a business on Kiva.org, you can "sponsor a business" and help the world's working poor make great strides towards economic independence. Throughout the course of the loan (usually 6-12 months), you can receive email journal updates from the business you've sponsored. As loans are repaid, you get your loan money back.